"Contrary to the initial fears of some, the results [in Portugal] have been reduced drug use, reduced overdose fatalities, reduced incarceration and a range of other positive outcomes," he wrote.

Andrew Meares / Fairfax
Kelly said that change was needed because "we are simply not going to arrest ourselves out of this problem".

Kelly said that despite having always thought that "we can't show any weakness" in regards to drugs, "we are simply not going to arrest ourselves out of this problem".

"I'm still not convinced a full decriminalisation is correct but I think we do need to put more resources into the rehabilitation sector to make sure that we can do everything we can to prevent people, to deter their will from taking drugs in the first place," he said.